Electrical fuel control system for internal combustion engines

ABSTRACT

An electrical fuel control system for internal combustion engines, wherein various data representing the operating conditions of an internal combustion engine are converted into digital signals which are operated on to generate such fuel controlling signals that suit the required characteristics of the engine, whereby the quantity of fuel injected as well as the spark timing are controlled to ensure the optimum amount of fuel injected and the optimum spark timing.

United States Patent 1191 Yoshida et a1.

ELECTRICAL FUEL CONTROL SYSTEM FOR INTERNAL COMBUSTION ENGINES Inventors: Hiroshi Yoshida; Noriyoshi Ando;

Kazuo Oishi, all of Kariya, Japan Assignee: Nippondenso Kabushiki Kaisha,

Kariya-shi, Japan Filed:

Jan. 26, 1973 Appl. No.: 327,603

Related U.S. Application Data Continuation of Ser. No. 126,830, March 22, 1971,

abandoned.

Foreign Application Priority Data Mar. 26, 1970 Apr. 7, 1970 Apr. 10, 1970 Apr. 15, 1970 Apr. 15, 1970 Apr. 22, 1970 U.S. Cl.'.... 235/l50.2l, 123/32 EA, 235/150.l,

Int. Cl..... F02d 5/00, F02d 37/02, G05b 15/02 Field of Search. 235/150.2l, 150.1, 151,

235/l51.l; 123/32 EA References Cited UNITED STATES PATENTS Guiot.....' 123/32 EA 1 June 11, 1974 OTHER PUBLICATlONS Williams: Electronic Fuel Injection ReducesAutomotive Pollution. Electronics Sept. 1972 Vol. ,45 No. 19, p. 121-125.

Primary ExaminerFelix D. Gruber Attorney, Agent, 0r Firm-Cushman, Darby & Cushman 5 7] ABSTRACT An electrical fuel control system for internal combustion engines, wherein various data representing the operating conditions of an internal combustion engine are converted into digital signals which are operated on to generate such fuel controlling signals that suit the required characteristics of the engine, whereby the quantity of fuel injected as well as the spark timing are controlled to ensure the optimum amount of fuel injected and the optimum spark timing.

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1. A fuel control system for internal combustion engines in which the fuel is Supplied through an electromagnetic valve to each cylinder of the engine by an amount which is predetermined as a non-linear function of at least one operational parameter of the engine, said system comprising: vacuum sensor means responsive to the intake manifold vacuum of the engine for producing an analog voltage signal proportional to said vacuum; a first analog to digital converter connected in circuit with said vacuum sensor for converting said analog voltage signal to a first digital signal in a binary code of a predetermined number of places; a first discriminator connected in circuit with said first analog to digital converter for detecting one of a plurality of predetermined pressure ranges within which said vacuum represented by said first digital signal stands, and producing a number of output signals as determined by said detected pressure range; first circuit means including a plurality of first shifted code setting circuits for each producing digital signals in binary codes which indicate respectively numbers represented by binary codes obtained by shifting said binary code of said first digital signal to the right successively by one place each shift, a first constant code setting circuit for producing a predetermined constant value, and first selecting means for selecting a number of circuits from said first shifted code setting and said first constant code setting circuits in accordance with said number of output signals of said first discriminator and permitting said digital signals produced by the selected circuits to pass therethrough; a first adder connected to said first circuit means for receiving said digital signals passed through said selecting means and adding them to produce an injection digital signal; and injection circuit means for energizing said electromagnetic valve of each cylinder, thereby effecting a fuel injection for a time interval whose duration is determined by said injection digital signal.
 2. A fuel control system according to claim 1, wherein said injection circuit means comprise: a memory circuit in circuit with said first adder for retaining said output digital signal of said first adder in a form of a binary code; a clock pulse generator for producing clock pulses with a predetermined frequency; means for producing a timing pulse which determines the starting of fuel injection during each cycle for each cylinder; a counter for counting said clock pulses transmitted thereto and producing an output digital signal in a binary code corresponding to the count; a comparator for producing an output signal for ending the energization of said electromagnetic valve under coincidence of the digital signal retained in said memory and that of said counter, and a distributor comprising means responsive to said timing pulse for starting and continuing energization of the electromagnetic valve of said each cylinder and simultaneously permitting said clock pulses, being transmitted to said counter from said clock pulse generator to pass therethrough and means responsive to an output signal of said comparator for ending the energization of said electromagnetic valve and simultaneously preventing thereafter said clock pulse from being transmitted to said counter.
 3. A fuel control system according to claim 1, further comprising: a speed sensor responsive to the speed of the engine for producing an analog voltage signal proportional to the engine speed; an inverter circuit connected in circuit with said vacuum sensor for producing an analog voltage inversely proportional to said vacuum; a second analog to digital converter connected in circuit with said inverter circuit for converting said analog voltage signal produced by said inverter circuit to a second digital signal in a binary code of a predetermined number of places; a third analog to digital converter connected in circuit with said speed sensor for converting said analog voltage signal produceD by said speed sensor to a third digital signal of a binary code of a predetermined number of places; a second discriminator connected in circuit with said second analog to digital converter for detecting one of a plurality of predetermined pressure ranges within which the vacuum represented by said second digital signal stands and producing a number of output signals as determined by said detected pressure range; a third discriminator connected in circuit with said third analog to digital converter for detecting one of a plurality of predetermined speed ranges within which said engine speed represented by said third digital signal stands and producing a number of output signals determined by said detected speed range; second circuit means including a plurality of second shifted code setting circuits for producing digital signals of binary codes which indicate respectively numbers represented by binary codes obtained by shifting said binary code of said second digital signal to the right successively by one place each shift, a second constant code setting circuit for producing a digital signal of a binary code indicating a predetermined constant value, and second selecting means for selecting a number of circuits from said second shifted code setting and second constant code setting circuits in accordance with said number of output signals of said second discriminator and permitting said digital signals of the selected circuits to pass said second selecting means; third circuit means including a plurality of third shifted code setting circuits for producing digital signals in binary codes which indicate respectively numbers represented by binary codes obtainable by shifting said binary code of said third digital signal to the right successively by one place each shift, a third constant code setting circuit for producing a digital signal of a binary code indicating a predetermined constant value, and third selecting means for selecting a number of circuits from said third shifted code setting and third constant code setting circuits in accordance with said number of output signals of said third discriminator and permitting said digital signals of said selected circuits to pass through said third selecting means: a second adder connected in circuit with said third circuit means and said second circuit means for receiving said digital signals produced by said second and third circuit means and adding them to produce an ignition digital signal; and ignition circuit means for advancing an ignition of each cylinder by a time determined by said ignition digital signal.
 4. A fuel control system according to claim 3, wherein said ignition circuit means comprise: a memory circuit for retaining said output digital signal of said second adder in a form of a binary code; an angular sensor for periodically producing pulses in accordance with rotations of the engine; a timing sensor for producing a timing pulse responsive to a predetermined position each cycle of each cylinder; a counter for counting pulses of said angular sensor transmitted thereto and producing an output digital signal of a binary code corresponding to the count; a comparator for producing an output signal upon coincidence of said digital signal of said memory circuit and that of said counter; a distributor comprising means responsive to said timing pulse for permitting said pulses of said angular sensor being transmitted therethrough to said counter; and an ignition circuit for producing an ignition timing signal responsive to said output signal of said comparator.
 5. A fuel control system according to claim 1 further comprising: a temperature sensor responsive to the engine temperature for producing an analog voltage signal proportional thereto; a second analog to digital converter connected in circuit with said temperature sensor for converting said analog voltage signal to a second digital signal in a binary code of a predetermined number of places; a second discriminator connected in circuit with said analog to digital converter for detecting one of a plurality of predetermined temperature ranges within which said engine temperature represented by said second digital signal stands and producing a number of output signals determined by said detected temperature range; a start sensor for producing a signal upon starting of the engine; second circuit means comprising a plurality of second shifted code setting circuits for producing digital signals of binary codes which represent respectively numbers represented by binary codes obtained by shifting said binary code of said second digital signal to the right successively by one place each shift, a second constant setting circuit for producing a digital signal of a binary code indicating a predetermined constant value, and second selecting means for selecting a number of circuits from said second shifted code setting and said second constant setting circuits in accordance with said number of output signals of said second discriminator and said signal of said start sensor and permitting said digital signals produced by said selected circuits to pass therethrough; and a first auxiliary circuit connected between said first adder and said injection circuit means and further connected to said second circuit means for correcting said insection digital signal produced by said first adder in accordance with said digital signals passed through said second selecting means and supplying said corrected injection digital signal to said injection circuit means.
 6. A fuel control system according to claim 5 further comprising: an engine speed sensor responsive to the engine speed for producing an analog voltage signal proportional to said engine speed; a third analog to digital converter connected in circuit to said engine speed sensor for converting said analog signal to a third digital signal of a binary code of a predetermined number of places; a third discriminator connected in circuit with said third analog to digital converters for detecting one of a plurality of predetermined speed ranges within which said engine speed represented by said third digital signal stands and producing a number of output signals determined by said detected speed range; a fourth discriminator connected in circuit with said first analog to digital converters for detecting one of a plurality of predetermined pressure ranges within which said vacuum represented by said first digital signal stands and producing a number of output signals determined by said detected pressure range; third circuit means comprising a plurality of third shifted code setting circuits for producing digital signals of binary codes which indicate respectively numbers represented by binary codes obtainable by shifting said binary code of said third digital signal to the right successively by one place each shift, a third constant code setting circuit for producing a digital signal indicative of a predetermined constant value, and third selecting means for selecting a number of circuits from said third shifted code setting and third constant code setting circuits in accordance with said output signals of said third discriminator and permitting said digital signals of said selected circuits to pass therethrough; fourth circuit means comprising fourth selecting means for selecting a number of circuits from said first shifted code setting and first constant code setting circuits in accordance with said output signals of said fourth discriminator and permitting said digital signals of said selected circuits determined by said fourth selecting means to pass therethrough; means connected to said third and fourth circuit means for summing the signals passed therethrough to provide an ignition signal; a first memory circuit for retaining a digital signal supplied thereto and connected to said injection circuit means for supplying the same with said digital signal memorizeD therein; a second memory circuit for receiving said ignition signal and retaining that ignition; and ignition circuit means connected to said second memory circuit for producing an ignition timing signal in accordance with said digital signal retained in said second memory circuit thereby effecting an ignition at a time determined by said retained digital signal.
 7. A fuel control system according to claim 5 wherein said first auxiliary circuit comprises: a second adder connected to said second circuit means for adding said digital signals produced by said second circuit means thereby producing a number of second addition digital signals determined by said addition; adder circuit means connected to said first adder and said second adder and comprising a plurality of addition code setting circuits for producing digital signals of binary codes which indicate respectively numbers represented by binary codes obtainably by shifting a binary code of said injection digital signal produced by said first adder to the right successively by one place each shift, and adder selecting means for selecting a number of circuits from said addition code setting circuits in accordance with said number of second addition digital signals and permitting said digital signals of said selected circuits to pass therethrough, and a third adder connected between said adder circuit means and said injection circuit means for receiving said digital signals passed through said adder selecting means and adding them totally thereby producing a digital signal which is supplied to said injection circuit means as an injection digital signal. 